Tests

• Test syntax
• Testing strings
• Version Comparison
• Set theory tests
• Test if a list contains a value
• Testing paths
• Task results

Tests in Jinja are a way of evaluating template expressions and returning True or False. Jinja ships with many of these. See builtin tests in the official Jinja template documentation.

The main difference between tests and filters are that Jinja tests are used for comparisons, whereas filters are used for data manipulation, and have different applications in jinja. Tests can also be used in list processing filters, like map() and select() to choose items in the list.

Like all templating, tests always execute on the Ansible controller, not on the target of a task, as they test local data.

In addition to those Jinja2 tests, Ansible supplies a few more and users can easily create their own.

Test syntax

Test syntax varies from filter syntax (variable | filter). Historically Ansible has registered tests as both jinja tests and jinja filters, allowing for them to be referenced using filter syntax.

As of Ansible 2.5, using a jinja test as a filter will generate a warning.

The syntax for using a jinja test is as follows:

variable is test_name

Such as:

result is failed

Testing strings

To match strings against a substring or a regular expression, use the “match”, “search” or “regex” filters:

vars:
  url: "http://example.com/users/foo/resources/bar"

tasks:
    - debug:
        msg: "matched pattern 1"
      when: url is match("http://example.com/users/.*/resources/.*")

    - debug:
        msg: "matched pattern 2"
      when: url is search("/users/.*/resources/.*")

    - debug:
        msg: "matched pattern 3"
      when: url is search("/users/")

    - debug:
        msg: "matched pattern 4"
      when: url is regex("example.com/\w+/foo")

‘match’ requires zero or more characters at the beginning of the string, while ‘search’ only requires matching a subset of the string. By default, ‘regex’ works like search, but regex can be configured to perform other tests as well.

Version Comparison

To compare a version number, such as checking if the ansible_facts['distribution_version'] version is greater than or equal to ‘12.04’, you can use the version test.

The version test can also be used to evaluate the ansible_facts['distribution_version']:

{{ ansible_facts['distribution_version'] is version('12.04', '>=') }}

If ansible_facts['distribution_version'] is greater than or equal to 12.04, this test returns True, otherwise False.

The version test accepts the following operators:

<, lt, <=, le, >, gt, >=, ge, ==, =, eq, !=, <>, ne

This test also accepts a 3rd parameter, strict which defines if strict version parsing as defined by distutils.version.StrictVersion should be used. The default is False (using distutils.version.LooseVersion), True enables strict version parsing:

{{ sample_version_var is version('1.0', operator='lt', strict=True) }}

Set theory tests

To see if a list includes or is included by another list, you can use ‘subset’ and ‘superset’:

vars:
    a: [1,2,3,4,5]
    b: [2,3]
tasks:
    - debug:
        msg: "A includes B"
      when: a is superset(b)

    - debug:
        msg: "B is included in A"
      when: b is subset(a)

Test if a list contains a value

Ansible includes a contains test which operates similarly, but in reverse of the Jinja2 provided in test. This is designed with the ability to allow use of contains with filters such as map and selectattr:

vars:
  lacp_groups:
    - master: lacp0
      network: 10.65.100.0/24
      gateway: 10.65.100.1
      dns4:
        - 10.65.100.10
        - 10.65.100.11
      interfaces:
        - em1
        - em2

    - master: lacp1
      network: 10.65.120.0/24
      gateway: 10.65.120.1
      dns4:
        - 10.65.100.10
        - 10.65.100.11
      interfaces:
          - em3
          - em4

tasks:
  - debug:
      msg: "{{ (lacp_groups|selectattr('interfaces', 'contains', 'em1')|first).master }}"

You can use any and all to check if any or all elements in a list are true or not:

vars:
  mylist:
      - 1
      - "{{ 3 == 3 }}"
      - True
  myotherlist:
      - False
      - True
tasks:

  - debug:
      msg: "all are true!"
    when: mylist is all

  - debug:
      msg: "at least one is true"
    when: myotherlist is any

Testing paths

The following tests can provide information about a path on the controller:

- debug:
    msg: "path is a directory"
  when: mypath is directory

- debug:
    msg: "path is a file"
  when: mypath is file

- debug:
    msg: "path is a symlink"
  when: mypath is link

- debug:
    msg: "path already exists"
  when: mypath is exists

- debug:
    msg: "path is {{ (mypath is abs)|ternary('absolute','relative')}}"

- debug:
    msg: "path is the same file as path2"
  when: mypath is same_file(path2)

- debug:
    msg: "path is a mount"
  when: mypath is mount

Task results

The following tasks are illustrative of the tests meant to check the status of tasks:

tasks:

  - shell: /usr/bin/foo
    register: result
    ignore_errors: True

  - debug:
      msg: "it failed"
    when: result is failed

  # in most cases you'll want a handler, but if you want to do something right now, this is nice
  - debug:
      msg: "it changed"
    when: result is changed

  - debug:
      msg: "it succeeded in Ansible >= 2.1"
    when: result is succeeded

  - debug:
      msg: "it succeeded"
    when: result is success

  - debug:
      msg: "it was skipped"
    when: result is skipped